The algae terraformed the earth

Stuart Hay/ANU

A planetary takeover by ocean-dwelling algae 650 million years ago was the kick, the life on the earth.

This is what geochemists argue that in nature this week, on the basis of invisible small traces of biomolecules unearthed in the Australian desert.

The molecules that select an explosion in the amount of algae in the oceans.

This, in turn, fuelled a change in the food web allowed us to develop the first microscopic animals, the authors suggest.

“This is one of the most profound ecological and evolutionary transitions in the history of the earth,” lead researcher Jochen Brocks said the BBC\’s Science in Action programme.

The events took place a hundred million years before the so-called Cambrian Explosion, an outburst of complex life recorded in fossils around the world, the confused Darwin, and always is implied, a kind of biological history.

Scattered traces of this precursor to multi-celled organisms have been recognized since a long time, but resulted in the evolutionary driver, whose ascent was already fighting a lot.

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University of Cambridge palaeontologist Nick Butterfield has said that the time “was probably the most revolutionary in Earth history”, and not only because of the rapid biological changes. There were violent fluctuations in climate, also, the experts have long suspected, are intertwined.

The context was a planet life so far, had a long conservation of the oceans and the mild climate. However, for over three billion years – since 3.8 billion years ago, according to most estimates – all life is bacteria, small evolutionary innovation was done single-celled, usually.

Algae, which are more complex than bacteria, but still single-celled, had to call for over a billion years (the “boring billion”, some paleontologists), but without much of an ecological impact.

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With its DNA core (so-called eukaryotic cells, like all animals and plants are safely stored in a cell today), you\’d use an evolutionary advantage over bacteria, they seemed to be able to.

That changed about 650 million years ago, according to the new study.

There are no fossils of algae. Instead, Brock and his team at the Australian National University, have molecular residues of the cell walls, molecules, the quips closely with the cholesterol in our body, “the most stable thing in each organism fat,” Brock tracked down.

After each track the cells expire, these fat molecules remained and were included in the sediments and, over geological time, was cemented in the underground of Australia. Drilled and analyzed hundreds of millions of years later.

“The signals we find, show that the algae population went up by a factor of a hundred to a thousand, and the variety went bang in a big”, and never went back,” Brock says.

This ecological flip happened shortly after one of the largest environmental disasters the planet has ever seen – the “snow ball earth” period, when the ice stretched from pole to pole and even at the equator, the temperatures could, plunged to minus 60 degrees.

The episode ended after 50 million years, as the accumulation of volcanic CO2 in the atmosphere creates a super green house, melted the ice in a second disaster.

Stuart Hay/ANU

The connection, Brock believes, is that the glacial action, the soil of the continental rocks, the release of the nutrient was phosphate and then washed into the oceans as the snow melt is advanced.

Today\’s agriculture green revolution is dependent on phosphates excavated in huge mines around the world, and the pre-Cambrian biologic revolution were powered the same way, the researchers.

“This increase in the algae happens just around the time of the first animals on the scene,” Brock explains. “It was algae at the bottom of the food chain, created this burst of energy and nutrients to develop larger and more complex living beings.”

Yale University, Noah Planavsky of their study, which reveals the beginning of this year [nature], the phosphate nutrient to the outbreak after the snow ball earth, says the new revelations “incredibly important”.

“There are the first signs of ecosystems dominated by complex living organisms – eukaryotes,” he told the BBC.

In a commentary, also in nature, Andrew Knoll of Harvard University, a world-recognized authority on pre-Cambrian life,” says the new work makes “a substantial contribution” unveiling “the relationship between life and the surrounding physical environment” at a critical moment in animal evolution.

“Food source changes may have helped to pave the way for the animal to radiation,” he agreed, though the addition of “core questions”.

Retrieve the data was a tedious job, says Roger Summons, who has previously, together with Brock\’s. The nanogram traces of pre-Cambrian oil had to be measured in the study are picked up from a fog of pollution from the fossil fuels.

“I welcome Jochen insight and tenacity,” Summon wrote in an e-mail. “The results show, as demanding attention to detail ultimately pays for itself.”

However, he recommends that the story is not yet complete. Similarly, University of Cambridge, Nick Butterfield, during the adoption of the data does not agree with the interpretation.

In fact, he thinks that Brock has cause and effect, from the rear to the front; the explosion of the algae, not the rise of animals, he says.

“There is no evidence for animal evolution restrictions imposed by a lack of food,” he argued in an e-mail.

Instead, he says, it was the rise of the animals – sponges, to be exact-that the evacuation of the ecological path for the algae.

Brocks and Butterfield discussed the interpretation in the corridors of the Goldschmidt geochemistry conference in Paris this week, as the other looked up.

Brock\’s remains unswayed, that the outbreak of algae 650 million years ago, “the launch upgrade for the escalating betting”, in which a larger creatures, favored by their ocean-grazing, the prey still larger, until you end up with the complexity that we see today.